Without the additive, you might have some filter issues. Algae is not a friend of diesel, in any type of storage. I also have seen fuel from 30 year old tanks used, however newer equipment will not tolerate it well. Hopefully you can kill it and filter it. Whatever blend they are using is not like 30 years ago. One wonders about the chemical nature of the ground shale oil.

Algae and microbes are usually more of a problem with outside tanks, due to the increased amount of moisture in the tank. Corrosion is another concern. Believe it or not, today's fuels can actually allow the tank to rust on the inside. The more moisture there is in the fuel, the worse it is. This summer my brother ended up with 3 bulldozers and an excavator shutdown due to contaminated fuel. The farmer's tank had moisture in the bottom, and there was a bunch of rust/sludge in the fuel that plugged the filters on the equipment.

Keep the tank inside if possible, use a filter on the outlet hose, and use a multi-purpose fuel treatment as well.

One other thing I read somewhere recently is it is more of a possibility for an explosion from static sparks. They now recommend a ground strap when transferring fuel. They keep making thing better don't they.

storage ability of todays diesel is fine. if industry can store it for decades so can you. Don't lose sleep over it.

Add a biocide, always make sure the tank is pitched and tapped at the bottom, and add a general fuel treatment. I like the products from powerservice. Store regular (summer) diesel #2 add biocide and general fuel treatment and you'll be fine.